Type 2 diabetes mellitus is one of the most common worldwide diseases. In 2007, its prevalence was estimated at 5.9% (246 million people) of the adult population and is in continuous increase. This disease is even more serious since it could lead to severe micro- and macro-complications, which could become disabling or lethal, as diabetes is a major risk factor for cardiovascular disease and stroke.
Type 2 diabetes is characterized by a fasted and post-prandial hyperglycemia, consequence of two main defects: an insulin resistance at the level of target tissues and an altered insulin secretion from the pancreatic beta cells. This latter anomaly seems to appear very as it is present at the Impaired Glucose Tolerance (IGT) stage (Mitrakou et al., N. Engl. J. Med. 326: 22-29, 1992). It has been observed in UK Prospective Diabetes Study (UKPDS) that 50% of the beta cell function is already lost when diabetes is diagnosed, suggesting that deterioration in beta cell function may begin 10-12 years before diabetes diagnosis (Holman, Diabetes Res. Clin. Pract. 40: S21, 1998 or UKPDS Group, Diabetes 44: 1249-58, 1995).
The defective insulin secretion is due to a quantitative and a qualitative defect of the beta cell, i.e. a decreased beta cell mass and a specific defect of insulin release in response to glucose, especially the first phase of secretion, since the response to non-glucose secretagogues is preserved (Pfeifer et al., Am. J. Med. 70: 579-88, 1981). The importance of restoring a normal profile of insulin release in response to glucose to maintain the glycemic control within a normal range was supported by studies in non diabetic volunteers showing that delaying the first phase of insulin secretion in response to glucose led to glucose intolerance (Calles-Escandon et al., Diabetes 36: 1167-72, 1987).
Oral antidiabetics available for treatment of type 2 diabetic patients, such as sulfonylureas or glinides, are known to induce insulin secretion, by binding to sulfonyurea receptor on the K-ATP channels of the beta cell, leading to increase in intracellular calcium and insulin exocytosis. This insulin release is thus totally independent of the plasma glucose level and treatment with these molecules usually induces sustained hyperinsulinemia, which could lead to several side-effects, such as severe hypoglycaemia, body weight gain, and aggravation of cardiovascular risk. In addition, the prolonged hyperinsulinemia observed with sulfonylurea treatment, with no preservative effect of the beta cell mass, could lead to secondary failure due to beta cell exhaustion, another deleterious side effect of these compounds.
New treatment of type 2 diabetes should restore a normal profile of insulin release specifically in response to glucose, while preserving or increasing the beta cell mass. This is observed with GLP-1 analogs, such as exenatide or liraglutide, but these molecules are peptides and must be administered by parenteral route.
Such characteristics for a new oral small molecule would be a great advantage over the other antidiabetic drugs.
According to the present invention, the compounds of the formula (I) are insulin secretion stimulators, useful for treatment of diabetes and pathologies associated. They lower blood glucose levels by restoring the defective glucose-induced insulin secretion in type 2 diabetics.
The patent application WO 2007071646 describes aryl and heteroaryl substituted pyrazinone derivatives having antagonistic melanin-concentrating hormone activity, usefull for the prevention and/or treatment of psychiatric disorders.
EP 927171 describes pyrazinones corticotrophin releasing factor antagonists for use in treating psychiatric and neurological diseases including major depression, anxiety-related disorders, post-traumatic stress disorders and eating disorders.